1. Field of the Invention
The present invention relates to laser metrology and more particularly to a laser system for determining the alignment and measuring wear of machine parts such as the barrels or bores of extruders.
2. Description of the Prior Art
Various laser systems are known for measuring and aligning machine parts and assemblies. Systems of this type are disclosed in applicant's U.S. Pat. Nos. 4,045,129; 4,297,031; 4,382,680; 4,483,618; 4,468,119; 4,679,940; 4,714,344; and 4,844,618. It is common in such systems, as in the system disclosed, for example, in U.S. Pat. No. 4,297,031, to require a number of setting-up operations involving centering the laser source and aligning the mounting parts and targets before beginning the actual assembling of machine parts, and their measuring and alignments. When working with machine parts having barrels and bores to be measured, it is desirable to fixture the laser and/or the target on the central axis of the bore or at some known distance from the centerline for properly performing the alignment. Various devices for monitoring or measuring the interiors of pipes and bores are disclosed in U.S. Pat. Nos. 4,218,923; 4,281,929; 4,523,640; 4,843,896; and 4,967,092. These devices typically involve a complex fixture for the laser or the target with arms or rods which expand in equal and opposite directions to center the laser or the target in the bore. These fixtures are mechanically complicated, with many parts that can cause inaccuracies, and include expensive components. Consequently, setting up and operating such systems can require trained technicians and time-consuming careful assembly and measurements as well as sophisticated and costly equipment. It is therefore a problem in the art to achieve fast and easy set-up and aligning when performing machine part alignment and centering operations and to accomplish it with uncomplicated and inexpensive instrumentation.